1. Field of the Disclosure
The present disclosure relates generally to a transmitter and, more particularly, to a transmitter that supports a Multi-Mode Multi-Band (MMMB).
2. Description of the Related Art
Generally, a mobile communication service is provided in different communication service schemes around the world and uses multiple frequency bands for each communication service scheme. For example, the different mobile communication service schemes include a Personal Communication Service (PCS), a Digital Cellular System (DCS), a Code Division Multiple Access (CDMA) scheme, a Global System for Mobile communication (GSM)/General Packet Radio Service (GPRS)/Enhanced Data rates for GSM Evolution (EDGE) scheme, a Wide band Code Division Multiple Access (WCDMA) scheme, a Long Term Evolution (LTE) scheme, etc. Further, the CDMA scheme uses frequency bands of 800 MHz, 1800 MHz, and 1900 MHz, while the GSM scheme uses frequency bands of 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. Additionally, the WCDMA and LTE schemes use frequency bands of 850 MHz, 1900 MHz, and 2000 MHz.
Conventional mobile terminals may be configured to use a signal of one or two frequency bands among the mobile communication services. Therefore, the conventional mobile terminals only use one or two mobile communication services. Accordingly, when a user visits an area providing a different communication service that is not the service the user's mobile terminal is configured to use, e.g., when traveling, the user cannot use the mobile terminal.
As a result, many users desire and many manufacturers are trying to provide a mobile terminal that is capable of receiving all types of mobile communication services around the world.
However, in order for a mobile terminal to use all mobile communication services and frequency bands for each of the services, the mobile terminal should support a Multi-Mode Multi-Band (MMMB).
“Multi-Mode” refers to, for example, a Frequency Division Duplex (FDD) mode according to the WCDMA scheme, a Time Division Duplex (TDD) mode according to the GSM scheme, etc., and “Multi-Band” refers to different frequency bands. For example, a MMMB, which supports the FDD mode and the TDD mode, i.e., two modes as the multi-mode, supports three service bands of WCDMA 2000, WCDMA 1900, and WCDMA 850 as the FDD mode, and also supports four service bands of PCS 1900, DCS 1800, GSM 900, and GSM 850, as the TDD mode may be supported in the mobile terminal. In WCDMA 2000, WCDMA 1900, WCDMA 850, PCS 1900, DCS 1800, GSM 900, and GSM 850, the numbers “2000”, “1900”, “1800”, and “850” signify that each frequency band is 2000 MHz, 1900 MHz, 1800 MHz, and 850 MHz, respectively.
An LTE system, however, applies Carrier Aggregation (CA) technology for supporting a high data transfer rate. In addition, LTE is required to support a Dual Subscriber Identification Module (SIM) Dual Active (DSDA) scheme, which simultaneously uses two communication company lines according to a characteristic of each country. For example, over a large geographic area such as China, a first communication provider provides a service in some areas and a second communication provider provides a service in other areas. Therefore, in order to receive the service from the first communication provider in some areas and receive the service from the second communication provider in other areas, the two communication company lines need to be simultaneously occupied.
Accordingly, a transmitter is needed, which supports MMMB, while considering the CA technology and the DSDA scheme.
In one approach, a transmitter may be implemented by an MMMB Power Amplifier Module (PAM), an additional PAM, and a module in which a Radio Frequency (RF) switch and a duplexer are integrated. However, although the MMMB PAM supports a multi-band, only one band can be operated. Therefore, the CA technology, which should bind multiple bands, cannot be supported.
As another approach, in order to support the CA technology, the MMMB PAM is divided into a Low Band (LB) and a High Band (HB). For example, a band signal output from the MMMB PAM for the LB and a band signal output from the MMMB PAM for the HB are combined, thereby implementing the CA. However, in this approach, to support the DSDA scheme, a separate 2 G PAM needs to be added. Therefore, to support the CA and the DSDA, three separate PAMs are needed. However, to use three or more PAMs requires increased power consumption by the transmitter and more connections for transferring signals, such that the transmitter is less efficient and its construction is more complicated.